Coal Fired Boiler
Coal-fired boilers are commonly used to produce steam for industrial applications. However, for smaller residential and commercial boilers, the cost of coal handling, ash disposal, and emissions control make them a less attractive option than boilers fired by fuel oil or natural gas.Coal is made primarily of carbon, hydrogen, nitrogen and oxygen. However, it can also contain impurities, such as mercury and sulfur, which present problems with regards to boiler flue gas emissions. The quality of coal ultimately depends on where it is mined. Because environmental conditions, such as temperature and pressure, vary from one location to another, the physical and chemical properties of coal used for fuel in boilers will differ considerably.
Advantages of Coal Fired Boiler
Ease Of Load And Reduced Work
For automated coal stokers, just add coal to the hopper of your furnace and let it burn. Obtaining reliable heat requires little effort. Wood needs a lot more time, effort, and labor than coal between cutting, stacking, and seasoning.
Coals Are Easily Stored
Coal is more energy per cubic foot and is resistant to rotting and insects, unlike wood, which takes a significant amount of space to keep and can contain bugs. Wood will also decay. Time is saved, and maintenance is kept to a minimum using fuel-feeding devices like augers and hoppers.
Round-the-clock Heat Source
Unlike many other energy sources like solar, wind, or hydro, coal is never impacted by the weather or the quantity of sunshine available each day. A coal-burning furnace is an excellent option for those who don't want to worry about backup energy because coal is a dependable fuel source.
High Quality Coal Releases A Lot of Heat
Anthracite coal burns efficiently with no odor or smoke and by heating water rather than air, a coal-burning furnace loses less heat. To get an idea of how much high-quality coal can produce, one ton of anthracite coal equals about 8,200-kilowatt hours of electricity.
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Energy-Saving Coal Fired Steam Industrial BoilerThe actual output of this type of boiler is generally about 10~15% higher than the nameplate outputAdd to Inquiry -
Pressurized Coal Fired Heating BoilerThe coal-fired hot water boiler is mainly used for heating and bathing. The hot water boilerAdd to Inquiry -
Pressurized Coal Fired Hot Water BoilerThe phase-change coal-fired hot water boiler is a high-efficiency steam-water heat exchangeAdd to Inquiry -
Fully Automatic Coal Fired Steam Boiler PlantThe coal - fired steam boiler is a new type of water - fire boiler. The boiler body is a new typeAdd to Inquiry -
DZL Type Chain Coal Fired BoilerSuper advanced furnace type: efficient heat transfer without ash, heat transfer performanceAdd to Inquiry -
Chain Economy Coal Fired BoilerCoal-fired hot water heating boiler is a new type of water and fire tube boiler developed by ourAdd to Inquiry
- Tel: +8615833999209
- Whatsapp: +8615833999209
- Fax: +86-318-7251808
- Email: info@hbhongze.com
- Add: 2 North Suheng Road, Raoyang County, Hengshui City, Hebei Province, China.
Why Choose Us
Our Factory
Founded in February 1994, China Hebei Hongze Boiler Manufacturing Co., Ltd. is a high-tech enterprise focusing on the design, manufacture and installation of boilers and environmental protection equipment. Is the state administration of quality and technology supervision, inspection and quarantine designated production of boilers and auxiliary machinery accessories professional manufacturers, has obtained a number of product patents.
Our Products
The boiler products produced by our company mainly include: WNS series 0.5-20 tons gas-fired boiler, SZS series 20-100 tons gas-fired boiler; DZL series 1 t - 200 t lan-burning carbon boilers, DZL series 1 t - 200 t coal-fired boilers, DZL series 1 t - 200 t biomass fired boilers. Among them, large coal-burning phase change pressure heating boiler and twin-body steam boiler series products have been China's national patents, since the launch of the market, by the majority of users love and praise!
Certifications
Our company has obtained a number of patent certificates in China, including the patent certificate of "pressurized phase-change hot water boiler" in 2011; Obtained the patent certificate of "dual-fuel CNC boiler burning biomass or coal" and the patent certificate of "biomass pellet boiler" in 2014; Obtained the patent certificate of "a micro coal atomization boiler" and "a micro coal atomization burner" in 2015; In 2016, I obtained the patent certificate of "a new type of low-carbon boiler with low nitrogen combustion" and the patent certificate of "a low-carbon boiler with low nitrogen combustion". The patent certificate of "one denitrification device" obtained in 2018; Obtained the patent certificate of "a dual-grate dual-body boiler" in 2019.
Our Service
Pre-sales service: Technical consultation at any time, patient guidance and communication;
Sales services: Help customers to design the plane layout, reasonable layout and guide the construction.
After-sales service: Always pay attention to and help every customer to solve all problems in the process of using our products.
Characteristics of coal for Coal Fired Boiler combustion
Carbon: Carbon is the primary combustible component in coal. The longer the formation age of coal, the higher the carbon content and the greater the bond strength, making it more difficult to burn.
Hydrogen: Hydrogen is an essential combustible component of coal, with a heat value of approximately 144,500 kJ/kg. The hydro content in liquid fuel is higher than in solid fuel.
Sulfur Exists In Coal Combustion In Three Forms: Organic sulfur (OS), mineral sulfur (MS), and sulfate sulfur (SS). Organic and mineral sulfur can participate in the combustion process, while sulfate sulfur usually exists as CaSO4, MgSO4, FeSO4, etc. These bonds do not participate in the combustion process but instead transform into slag. The heat value of sulfur is approximately one-third of carbon. When sulfur burns, it produces SO2 or SO3 gases, which, when combined with water vapor in the combustion chamber, can form sulfuric acid (H2SO4), corroding metals, and damaging boiler systems. SO2
emitted into the environment is a hazardous toxic gas.
Oxygen and Nitrogen: Oxygen and nitrogen are inert substances in coal. Their presence reduces the combustible content of coal, resulting in lower heat value. Nitrogen does not participate in the combustion
process but is converted into free form in the smoke. The younger the coal, the more oxygen it contains.
Heat value: The heat value of coal is the amount of heat released when one kilogram of coal burns completely. Coal is classified based on its heat value, ranging from high to low. Coal is primarily carbon-based, with a heat value of approximately 34,150 kJ/kg of carbon. Therefore, the higher the carbon content, the higher the heat value of coal.
Moisture content: Moisture content is the amount of water contained in coal. The total moisture content of coal is determined by drying the fuel in an oven at 1050℃ until the fuel weight no longer changes. The weight loss is called the moisture content. In reality, at this temperature, not all moisture is completely removed from coal; some types of moisture, such as crystal moisture, usually require temperatures of 500-800℃ for complete evaporation.
Ash content: Ash content is the residue remaining after coal combustion. Mineral substances in coal transform into ash when burned. The presence of ash reduces the combustible content of coal, affecting its combustion. The ash ratio in coal greatly affects its combustion ability, reducing heat value, causing surface erosion of heat-absorbing tubes, accumulating dirt, and reducing the heat transfer coefficient across tube walls. Additionally, an important characteristic of ash significantly affecting the operation of combustion equipment is the ash fusion temperature.
Volatile matter: When fuel is burned under conditions where there is no oxygen in the environment, the bonds of organic molecules are broken. This process, known as thermal decomposition, produces gaseous substances, including hydrogen, hydrocarbons, carbon monoxide, and carbon dioxide. The products of thermal decomposition are called "volatile matter." Bonds with more oxygen are less stable and break more easily at high temperatures. The amount of volatile matter produced depends on the formation age of the coal; the younger the coal, the lower the temperature at which volatile matter begins to form. The amount of volatile matter produced also depends on the duration of thermal decomposition; the younger the coal, the shorter the duration of thermal decomposition, resulting in more volatile matter produced, leading to greater fuel consumption during combustion.
Coal-fired boilers have the same operating principles as other boilers, which are to heat water and provide heat for industrial production and processing. The amount of heat that a coal-fired boiler produces is from burning coal and firewood fuel, and then conduction of heat turns the heat energy into steam. Details of operation of coal fired boiler are as follows:
The fuel used to burn and the heat passing through the nozzle is put into the fire chamber to explode, heating the water pipes. Later, the water in the pipe boils up and forms steam. This steam is actually a mixture mixed with water that is brought up to the steam drum separating the steam from the water, the water that has not yet evaporated will return to the tubes to continue the circulation process.
The amount of steam separated at the time of leaving the steam drum will reach the superheater to form high temperature steam. Depending on the requirements of each user, which chooses to go into separate operation, the amount of smoke will be passed through the dust separator and discharged to the outside of the chimney. The unit uses the excess heat of the smoke as it is separated from the superheater for heat-intensive operation.
The Main Components Of A Coal Fired Boiler
The three main components of all boilers are the burner, combustion chamber and heat exchanger.
Burner
One of the most important parts of a boiler is the burner. This is where the mixing of the air with the fuel source happens, resulting in the combustion which provides the necessary heat to heat up the fluid.
The burner provides heat input by combustion of a heat source. In other words, it initiates the combustion reaction within the boiler.
The way this particular component operates is that thermostats will send messages to the burner electronically when the system needs to produce heat. And then, fuel will pump, by a filter mechanism, to the boiler from an outside source — usually an adjacent fuel tank. A nozzle on the burner turns this fuel into a fine spray and ignites it, which creates the reaction in the combustion chamber.
Combustion Chamber
As the name suggests, a combustion chamber is the part of a boiler in which the fuel/air mix burns. For this reason, the combustion chamber is usually cast iron, and the temperatures inside will rise to several hundred degrees. This process usually occurs in a very short amount of time. After the combustion, the heat generated in this chamber transfers to the boiler's heat exchanger.
Heat Exchanger
A heat exchanger is a component of a boiler that allows heat to be exchanged between two fluids or substances, usually water and gas, without letting the substances mix together. The heat exchanger of boiler allows the heat from the burner to heat the water in system. The job of the heat exchanger is to carry the heat from the burner to the water without having direct contact with the water. It's a similar idea to boiling water in a pot.
The heat exchanger transfers the heat produced by the burners within the combustion chamber to the water in the boiler. Heat exchangers can be made up of a variety of elements, including bundles of steel tubes, cast iron or copper lines. The elements need to be made of very sturdy material that is able to withstand high temperatures, last a long time and transfer heat efficiently. The process begins with hot gas and cold water, but because of the heat exchanger, the process ends with cooler gas and hotter water. All this transformation happens without the two substances even having to meet.
Equipment Required to Meet Coal Fired Boiler Safety
Safety Valve: Installed in accordance with the manual. When a safety valve is installed, it is legally prohibited to install a shut-off valve in the steam pipeline. It is not acceptable to diminish the safety valve's ventilation surface. The responsible authority must annually inspect and seal safety valves. The boiler operator is not permitted to modify the safety valve's operating conditions in any way.
Pressure Gauges: Each device must have pressure gauge 01 installed in a conspicuous place, protected against collisions and checked annually.
Plumbing Set: Includes dark water pipe, light water pipe, and boiler shut-off valve. Light water pipes must be impact-protected and labelled with the highest and lowest water levels per manufacturer's recommendations. To ensure optimum functioning, the water level indicator electrodes must be routinely checked.
Water Supply Pump: To avoid a water shortage that could cause the boiler to overheat and distort, the water supply must have sufficient capacity, pressure, and flow (high risk of fire and explosion). The water pump's electrical system needs to be shielded against electrical leakage.
Pressure Relay: Used to keep the boiler's operational pressure within acceptable bounds. Pressure relays need to be properly positioned when installed, checked frequently, and protected from deformation.
Blowdown Valve: To clean out the water tank's inside of water and lime scale for long-term boiler protection. When the boiler is working at operational pressure, water and scale are removed through the blowdown valve.
Steam Release Valve: Used to expel steam during accidents and boiler combustion. The trigger needs to be taken outside the plant to a secure location.
What Affects the Efficiency of a Coal Fired Boiler
Boiler Maintenance
It is crucial to maintain the boiler from time to time if you are keen on sustaining its efficiency. The thing is, the boiler's efficiency tends to deteriorate with time. As time goes by, its heat exchanger will start to be coated with dirt, ash, and other unwanted things that compromise its ability to function seamlessly. However, maintaining it regularly will eliminate such things and ensure smooth functionality.
Cleaning the coal-fired boiler is straightforward. You need to clean the heat exchanger surfaces. While doing your maintenance, it is vital to look out for any parts that are damaged or worn and replace them as soon as possible. Failing to undertake regular maintenance will culminate in heightened fuel consumption, compromised efficiency, and a long-term increase in maintenance costs.
Quality of the Fuel
The fuel quality plays a role in the efficiency of the coal-fired boiler. Coal fuel comes in different variants depending on the source. Some coal variants tend to possess more energy content, some more ash, and some have a high amount of fine ash. Nonetheless, the best coal quality will incorporate a low content of moisture, a high-calorie value, and a low ash content. Together with that, the coal should have a consistent shape and size and no fines or dirt.
Boiler Design
It is all about design when it comes to how the coal-fired boiler functions and its overall efficiency. The critical points of an efficient heat exchanger are the surface area of the heat transfer, furnace shape or size, and location. An ideal boiler design cuts down on the heat lost to the chimney. The higher the flue temperature means you send usable heat up the chimney.
Operating Conditions
The efficiency of a coal-fired boiler is dependent on its operating conditions. Some operating conditions that determine how well it performs include the airflow rate, feedwater temperature, and water flow rate. All these factors have a significant impact on the effectiveness of the burning process. The attributes are essential in transferring heat and burning coal completely. Therefore, it is crucial to maintain the best operating conditions to mitigate wastage and maximize energy output.
FAQ
As one of the leading coal fired boiler manufacturers and suppliers in China for over 25 years, we warmly welcome you to buy cost-efficient coal fired boiler made in China here from our factory. Good service and competitive price are available. Contact us for quotation.
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